This disclosure relates to a novel adapter (i.e., guide or chuck) for use in a mine roof bolting apparatus that permits conversion of the roof bolter into core drilling apparatus. The disclosure also relates to a method of converting the bolting apparatus and obtaining a core sample.
Underground mining machinery includes specialized apparatus adapted to carry out the operations required for obtaining the desired materials from the earth while maintaining mine integrity and safety. These include longwall mining systems, continuous mining machines, loader machines, face-haulage vehicles, roof or rock, bolters, and comparable mining vehicles and equipment.
Currently there are about 2,000 underground mines operating in the United States, including about 1,200 to 1,400 coal mines, about 500 to 600 mineral mines, and about 100 stone mines. In all underground mines, roof bolting is an operation that is essential in maintaining the integrity of a horizontal mine, helping to keep the roof of the mine from collapsing after material has been excavated from the mine face. The safety of the miners working in the mine environment thereby is enhanced. After material has been removed from the face of the mine, bolts are inserted and set into the roof of the mine to keep the roof from collapsing onto the workers. In order to improve safety, some mining machines have integrated the roof bolting apparatus into continuous mining machines, thereby reducing the risk of roof collapse. Since roof bolting is one of the most dangerous operations in underground mining, roof bolters that work ahead of the continuous mining machines are being developed. These pre-mining bolters drill into the seam to be mined and insert bolts at this early stage, thereby greatly reducing the risk of roof collapse. These newer roof bolter units may incorporate contemporary robotics technology.
U.S. Pat. No. 4,158,520 discloses a rock bolting apparatus in which a rock drill and a rock bolt setting device are interchangeable on a single elongated guide of a feed beam. When the rock drill is in operative position on the feed beam, the bolt setting device hangs on the side of the feed beam, and vice versa.
U.S. Pat. No. 4,420,277 discloses a mobile integrated apparatus for bolting the roof of an underground mine. The apparatus includes a mobile frame, a boom extending from the frame, and a housing provided at the end of the frame. The housing supports a drilling mechanism including a drill centralizer having a central bore therethrough and a passageway in communication with the central bore, a device for delivering a container of roof bolting anchoring media through the passageway, through the drill centralizer, and into a drilled hole, a device for indexing a roof bolt into alignment with the drilled hole and a spinner for driving the roof bolt into the drilled hole.
U.S. Pat. No. 4,759,888 discloses a means and method related to automatically installing full length grouted bolts as well as tensioned grouted bolts, which ensures proper shredding of the grout package, and proper mixing and curing of the grout. The inventive means further allows control of the depth of holes drilled for rock bolting and automatic freeing of drill steels.
U.S. Pat. No. 4,740,037 discloses a continuous mining machine including several components involved in cutting and conveying mined material, as well as a roof bolter. As a subframe is moved away from a main frame, the bolter is operated simultaneously with cutting to perform roof bolting operations close to the face of the mine.
U.S. Pat. No. 4,702,328 discloses a mine roof-drilling system including a lower surface of a retainer fixed to the drill head with an aperture formed therein to define a bearing surface for utilizing the drill head itself to pull the assemblage of drill steel from a completed bore.
U.S. Pat. No. 4,398,850 discloses a roof bolter and process for resin bolting a mine roof. Using two positions, the bolter drills and inserts resin in one position, and inserts a bolt in a second position. The invention also includes a device designed for attachment to a three-position resin type roof bolter to convert it into a two-position resin type roof bolter.
Much information relating to the strength and stability, or conversely, the weakness and instability, of strata that may overlay a newly-created mine roof, may be gleaned by an examination of the stratified geological structures present above the mine roof. For example, examination of such stratification could provide information to guide mine operators relating to the number of roof bolts required for a particular mine roof, as well as the lengths of roof or rocks bolts that may be required. Currently, such information is not obtained during the roof bolting and development stages.
There is therefore a need for providing a means of readily obtaining core samples from the roof of an advancing mine. There is furthermore a need for minimizing the number of pieces of equipment needed to carry out such coring operations, since the space available in advancing mine development areas is severely limited. Provision of a modular apparatus that could be used for both roof bolting and roof coring operations would be greatly advantageous. The present disclosure recognizes these needs.
The present disclosure provides a guide, or adapter, for converting a mine roof bolter into an apparatus suitable for guiding a coring rod, or drill, into a mine roof and obtaining a core sample. Information from such core samples can be used to evaluate the roof structure and more accurately determine mine bolt placement.
The guide may include a pair of jaws, each jaw having an adapter end and a pivotable end, with the pivotable end of each jaw being pivotally coupled to the pivotable end of the other jaw, means yieldably biasing the jaws to an open position with respect to each other, and the adapter end of each jaw includes a jaw cavity that faces the jaw cavity included in the adapter end of the other jaw, with each jaw cavity having a cross section that forms an arc of a circle with a central axis, wherein when the jaws are closed to a maximal extent, the jaw cavities form between them at least a major portion of a cylindrical coring cavity in which the central axes of the jaw cavities are disposed substantially on a common cylinder axis, the coring cavity having a cavity cylinder diameter substantially equal to the coring diameter, and adapted to enclose or grasp a coring rod, or drill, therein. In one embodiment, each jaw includes means for holding the rod guide within the mine roof bolter such that, when the coring rod is positioned between the jaws and the jaws are closed such that they enclose or grasp the rod, the roof bolter may engage the coring rod causing it to penetrate the mine roof and obtain a core sample, thereby converting the mine roof bolter into a mine roof coring apparatus.
In a preferred embodiment of the rod guide, the means to bias the jaws to an open position with respect to each other includes at least one spring element having two ends, with one end coupled to one of the jaws and the other end coupled to the other jaw, and operable to yieldably bias the jaws toward maintaining the jaws in a position opened to an extent sufficient to permit a coring rod to be placed between the jaws.
In an additional preferred embodiment, means for fixing the rod guide within the mine roof bolter may be one or more tabs or projections that match a receiving recess in the mine roof bolter.
In another aspect, a method of obtaining a core sample from a mine roof is disclosed. The method includes the steps of providing a coring rod guide adapter having a pair of opposed jaws having jaw cavities therein which together define a cylindrical coring cavity having a diameter substantially equal to a coring diameter, and placing the rod guide within a pair of guide members, inserting a coring rod into the coring rod guide such that the rod guide grasps or encloses the coring rod, engaging the coring rod with means for impelling the coring rod into the mine roof, causing the roof bolting apparatus to impel the coring rod into the mine roof, and withdrawing the coring rod with a core sample contained therein from the mine roof thereby obtaining a core sample.
The present disclousre is mainly directed to obtaining core samples from mine roofs in order to obtain information and data regarding the structure of the overlying strata and to determine bolting strategies to provide a safe work environment. Of course, as those skilled in the art will realize, the rod guides and methods of this disclosure can also be used in other drilling and core sampling applications such as, for example, rib or mine wall drilling, long hole drilling, and the like. In these applications, the rod guide would be used in the same manner as for roof bolting except that the drilling angle of the rock or roof bolter would be modified as appropriate. For purposes of this disclosure, reference to mine roofs, roof bolting, roof coring, and the like is intended to also include these alternative drilling/coring and applications.